Connectivity problems in a WLAN network can occur if you use the mobility network-id command incorrectly. You use the mobility network-id command in order to configure Layer 3 mobility in a wireless network. This command is meant to be used when the AP participates in a wireless domain services (WDS) infrastructure with a WLAN services module (WLSM) (that acts as the WDS device) where there is Layer 3 mobility.
Therefore, when an AP is configured as a WDS device, do not use the mobility network-id command.
If you use this command incorrectly, connectivity problems in the WLAN network result, such as:
Clients do not get IP addresses from the DHCP.
Clients cannot associate with the AP.
A wireless phone cannot be authenticated when you have a voice-over WLAN deployment.
So, if yur network uses AP as WDS, it doesnt have layer-3 mobility. So, this command will introduce unexpected results.
Refer the section "Usage of mobility network-id" section of "http://www.cisco.com/en/US/products/hw/wireless/ps430/products_tech_note09186a00800a86d7.shtml#ssid"